The inventive concepts relate to semiconductor memory devices and, more particularly, to semiconductor memory devices with improved reliability.
Semiconductor devices have been highly integrated to provide high performance and low costs. The integration density of semiconductor devices may affect the costs of the semiconductor devices, thereby resulting in a demand of highly integrated semiconductor devices. An integration density of a conventional two-dimensional (2D) or planar semiconductor memory device may be mainly determined by an area occupied by a unit memory cell. Therefore, the integration density of the conventional 2D semiconductor memory device may be greatly affected by a technique of forming fine patterns. However, since extremely high-priced equipment may be used to form fine patterns, the integration density of 2D semiconductor memory devices continues to increase but is still limited.
Three-dimensional (3D) semiconductor memory devices including three-dimensionally arranged memory cells have been developed to overcome the above limitations. However, production of 3D semiconductor memory devices may be expensive as compared with 2D semiconductor memory devices and may have concerns regarding providing reliable device characteristics.